Heather Christo’s Root Vegetable Gratin is a luxurious, gourmet side dish that brings together a medley of earthy root vegetables—celery root, yam, golden beet, rutabaga, turnip, and fingerling potatoes—layered with a rich, cheesy Mornay sauce. The vegetables offer a delightful range of flavors: the sweetness of yam and golden beet, the freshness of celery root, the buttery notes of rutabaga, and the peppery kick of turnip. Topped with fresh thyme and a drizzle of truffle oil, this gratin delivers creamy, decadent bites with a lovely earthy aroma, making it a perfect addition to holiday meals or special occasions.